There is no need to talk to anyone.
If the shipment does not show delivery on eBay* you can open an Item Not Received Claim and be refunded.
You can make a Claim only when the last estimated date for delivery has passed, which is has.
If that fails, you are also covered by the chargeback policy of credit card you really paid with, but start with the eBayClaim, it's faster, simpler and has more effect on the seller's account.
*As msau says, the seller's claim is irrelevant.